As a control device of this kind, there is known a control device that causes a fuel injection valve to perform multiple injections consisting of a main injection and a plurality of pilot injections preceding the main injection, as disclosed in, for example, Japanese Unexamined Patent Application, Publication No. 2009-299496. More particularly, the pilot injections are performed by injecting and combusting a very small quantity of fuel so as to increase in-cylinder temperature of an internal combustion engine prior to the main injection for the purpose of reducing a delay of ignition timing after the main injection and thus reducing NOx (nitrogen oxide) emissions while suppressing noise (combustion noise) produced as a result of the combustion. On the other hand, the main injection contributes to torque production of the internal combustion engine and has the largest injection amount among the multiple injections.
Meanwhile, with the aim to further improve the combustion condition of an internal combustion engine, there is also provided a technology for emitting an electromagnetic wave to a combustion chamber of the internal combustion engine, as disclosed in Japanese Unexamined Patent Application, Publication No. 2009-287549. More particularly, an antenna is arranged in the combustion chamber, and by means of the antenna, the electromagnetic wave is emitted, thereby generating plasma in the combustion chamber. Since OH radicals and the like are generated in the combustion chamber when the plasma is generated, the OH radicals and the like thus generated come to bind to fuel sprays. Accordingly, it is possible to promote ignition of the fuel sprays, and thus, it is possible to improve combustion condition of the internal combustion engine.